I created this plugin to help when creating sites that have fixed headers, if you fix the header to the top of the screen you then have to go in and add additional styles for logged in users that have the admin bar, after doing this on quite a lot of sites I thought a better way to manage this might be to allow the admin bar to be toggled in and out of view on the front end, whilst still keeping everything fixed to the top of the browser!
The plugin simply adds a button to the far right of the admin bar, shifting the whole bar up past the top of the screen (out of view) except for the button, on click of the button the admin bar slides into view.